The invention relates generally to scintillator materials for use in diagnostic imaging systems. In particular, the invention relates to methods of making single crystal scintillator materials and methods of using the same.
Typically, radiation is employed in a variety of fields such as medical diagnostics and non-destructive inspection. For example, X-ray computed tomography (CT) and a positron emission tomography (PET) are employed for medical diagnosis. Such X-ray or gamma ray radiation based devices employ a scintillator-based detector.
As will be appreciated, scintillators are generally used to convert gamma rays, X-rays or visible light into optical photons which can then be detected by a wide variety of different photosensors. Usually, it is desired to have a scintillator that has a high density, a short decay period of luminescence, and exhibits high resistance to radiation or stopping power. Further, in these applications, it is desirable to employ a transparent single crystal scintillator to enhance light properties.
However, transparent single crystals are difficult to grow, and are usually expensive due to high temperatures and expensive arrangements required to form the single crystals. Often single crystals are formed by converting their respective polycrystalline materials into melt form and subsequently growing a single crystal from the melt by using a seed crystal. These processes are expensive and time consuming. Further, there are limitations of the liquid solubility, which results in saturation of a species in a liquid melt beyond a concentration that exceeds solubility limits. Therefore, the composition of the scintillator materials is restricted in such methods by liquid solubility. For example, the amount of activator ions may be limited by the liquid state solubility of the activator ions in the melt. Furthermore, the activator ions may not be homogeneously distributed in the liquid melt or may not be homogeneously distributed in the single crystal formed from the liquid melt.
Accordingly, there is a need for methods of making a single crystal scintillator material, which has high transparency and desirable amounts of activator ion concentration, and is suitable for applications, such as CT and PET and that is cheaper and easier to make than by conventional techniques.